In the film, Brie Larson plays a young woman who’s been kidnapped and imprisoned in a single-room garden shed for years. She’s raped by her captor (Sean Bridgers), ultimately giving birth to a son, Jack (Jacob Tremblay).

Mother and son struggle to pass the time and stay sane, all while contemplating methods of escape.

The two most relevant real-world cases are the Josef Fritzl and Ariel Castro kidnappings.

Fritzl kept his daughter, Elisabeth, locked in the basement of their Austrian home from 1984 to 2008. She was raped repeatedly and gave birth to multiple children.

The film also borrows one of Elisabeth’s escape ideas. When her child fell ill in 2008, she convinced her father to take the girl to a hospital. Elisabeth secretly put an SOS note in her daughter’s pocket.

That hospital visit ultimately set in motion the events that would lead to Elisabeth’s rescue. Upon her release, the woman’s skin (like Larson’s) was pale and blotchy, a result of a poor diet and years of living without sunlight.

Josef Fritzl fathered seven children with a daughter he held captive in a squalid cellar for 24 years.AP Photo/Helmut Fohringer, Pool

Elisabeth’s children, some of whom had never left the cellar, were understandably confused by the outside world. Son Felix reportedly spent much of his time after his release stroking grass on a lawn.
“For them a passing cloud is a phenomenon,” one of the children’s doctors said at the time.

Cleveland’s Castro case is nearly as infamous. Ariel Castro kidnapped three young women and kept them inside his rundown house for between nine and 11 years, locking doors and bolting wood over the windows.

Like Larson’s characters, the captives found themselves making the most of everyday objects. Amanda Berry spoke of turning a cereal box into a picture frame.

Berry was also raped and gave birth to a daughter, Jocelyn, who was then held captive with her mother. Berry tried to make the child’s experience as normal as possible, despite their imprisonment. The two would pretend to walk to school each morning.

“I would tell her, ‘OK, we’re at a street now, so you have to stop. Then you look both ways for cars and then we can go across the street. OK, we’re at school now,’ ” Berry said.

Berry would drop her daughter off at a desk and then pretend to be a teacher, giving Jocelyn lessons and reciting the Pledge of Allegiance.